[Math] Simple graph with 6 vertices and 11 edges

graph theory

Show that a simple graph with $6$ vertices, $11$ edges, and more than one component cannot exist.

I don't understand why can't there be a simple graph with those edges and vertices. By definition of graph we have $|\text{Edges}| \geq |\text{Vertices}|-|\text{components}|$

So from this definition it's correct: $11 \geq 6-w$

Best Answer

If a component has only one vertex it has no edges, and the remaining five vertices can have at most 10 edges.

If a component has two vertices it gets worse since that component has only one edge, and the remaining 4 vertices have at most 6 edges. Other cases just as bad.